Originally posted by KRaZiGLiTcH Thanks i will most likely try this soon ^_^,Then how do i AF on something that is small and far away ? is that when MF comes in.
you obviously do not let the A3 sheet get out of the view finder because the way the focus works simply put is that it looks for contrast so black and white gives it something to lock on.
what you find is that as you point at the plain paper only the camera will hunt looking for something to focus on and until you slowly move to wards the cross it will do so till the drawn black cross starts to edge into the edge of the sector area and then it will focus . you need to be on a tripod and you will soon see that although the red dot is not acually on the cross the camera has focused.
you will also discover that this distance from the cross is not the same from side to side and top to bottom.
once you realize that [A] the focus is not exactly only on the red spot and [B] that the camera is using is a contrast edge/s to focus on you will understand why in the case of your example image the sign was used.
as previously pointed out i would suggest that you will have had the centre red selection area on the face and the sign is well within the selection area and is a strong contrast point